<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div{
            width: 50vw;
            height: 50vh;
            padding: 30px 20px 10px;
            border: 1px solid black;
            background-color: skyblue;
            margin: 20px 30px;
            border-radius: 50%;
        }
    </style>
</head>
<body>
    <div>
        这是DIV
    </div>
</body>
</html>